Hi Fred,
That's pretty neat.
However, you do know that by giving your grand kids toy guns, that you are sentencing them to a life of violent behavior?
Reminds me of the old Barney Miller program. In one episode, Barney comes home from a rough day at the station. His young son runs up with a toy gun, points it at him and yells "BANG!" Barney takes it away from him and hands him a toy car and says, "Here, play with this." The boy looks at the toy car, points it at Barney and yells "BANG!"